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July 13, 1998

UCSC researcher wins top paleontology award

By Tim Stephens

Paul Koch

The Paleontological Society has bestowed the 1998 Charles Schuchert Award on paleontologist and geochemist Paul Koch, an assistant professor of earth sciences. The Schuchert Award is presented annually to a researcher whose work early in his or her career reflects excellence and quality in the science of paleontology.

Koch will formally receive the award October 27 at the Paleontological Society's luncheon at the annual meeting of the Geological Society of America in Toronto.

Koch's research involves analyzing the chemical composition of fossils for clues to the biology and ecology of extinct animals. His work also sheds light on prehistoric changes in Earth's climate.

In one project, Koch and his coworkers analyze mineral deposits on fossil bones to document changes in the climate on land during a period around 50 to 60 million years ago when most of the modern groups of mammals first appeared. These mineral deposits reveal the oxygen isotope composition of rainfall at the time they were formed, a measurement closely tied to the mean annual temperature.

One of the main thrusts of Koch's research is to understand the ecology of Pleistocene-era mammals, such as mammoths and mastodons, in North America. The last appearances of these animals in the fossil record date to around 13,000 years ago. This coincides with a period of rapid climatic shifts at the end of the last ice age. In addition, the first hard evidence for substantial human populations in North America also dates precisely to this period.

Paleontologists have long debated what caused the extinction of the Pleistocene "megafauna," which included mammoths, mastodons, and sabre-toothed tigers. Was it human hunting, climatic change, or a combination of the two that did them in?

To address this question, Koch focuses on evidence recorded in the chemistry of fossil teeth. For example, the ratios of different carbon isotopes in teeth can reveal the types of plants on which an animal fed. Koch is interested in whether animals with a diverse diet were more likely to survive than those dependent on a specialized diet. Other chemical analyses provide evidence of the animals' migratory patterns and how climatic changes affected migration.

This work is helping Koch and others piece together a detailed picture of the Pleistocene environment and how it shaped the ecology and evolution of plants and animals in North America.

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